This grant application requests partial support for a Research Workshop entitled "Infantile Hemangiomas: Current Knowledge, Future Directions" to be held April 7-9, 2005 at the Lister Hill Auditorium on the NIH Campus and Pooks Hill Marriott in Bethesda, MD. This meeting has been initiated by the Hemangioma Investigator Group, a group from 7 pediatric dermatology centers who began in 2001 to meet and develop studies and mechanisms for furthering hemangioma research. It is sponsored by the University of California, San Francisco, Department of Dermatology. The organizing committee is represents a diverse group of specialties including hematology-oncology, dermatology, pathology, molecular medicine, and surgery. Although systematic, funded research on infantile hemangiomas has been lacking, the past 5 years have been a period of expanding interest and insights into this most common tumor of infancy. Although many hemangiomas are innocuous, a significant sub-set causes morbidity, which is life-altering or potentially life-threatening. There are currently no FDA approved medical treatments. The main treatment, systemic corticosteroids have never been studied in a controlled fashion and their mechanism of action is unknown. Other treatments, such as alfa-interferon and vincristine can be effective but have potentially serious side- effects. Recent studies suggest that hemangiomas may derive from angioblast-like cells with characteristics similar to the placenta microvillus vasculature. Advances in the understanding of angiogenesis and blood vessel formation are beginning to lead to a better understanding of pathogenesis. This meeting, the first ever of its kind, will be broadly interdisciplinary, including pathologists, surgeons, ophthalmologists, neurologists, molecular biologists, geneticists, and dermatologists. Its goal is to provide a forum for cross-fertilization of ideas, identification of key priorities for future research, and consideration of new-targeted therapies. Special attention is paid to involvement of young investigators and under-represented communities.